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  PROCEEDINGS 
  OF 
  THE 
  MALACOLOGICAL 
  SOCIETT. 
  

  

  Finally, 
  although 
  the 
  views 
  expressed 
  by 
  Forbes 
  and 
  Spratt 
  may 
  or 
  

   may 
  not 
  be 
  acceptable 
  at 
  the 
  present 
  day, 
  it 
  is 
  claimed 
  that 
  those 
  

   authors 
  should 
  be 
  recognized 
  as 
  having 
  first 
  demonstrated 
  the 
  existence 
  

   of 
  certain 
  variations 
  of 
  sculpture 
  among 
  the 
  Upper 
  Tertiary 
  lacustrine 
  

   shells 
  of 
  the 
  Island 
  of 
  Cos, 
  smooth 
  forms 
  only 
  being 
  found 
  in 
  the 
  

   lowest 
  or 
  oldest 
  beds, 
  whilst 
  those 
  of 
  more 
  complicated 
  ornamentation 
  

   were 
  restricted 
  to 
  the 
  upper 
  or 
  later 
  deposits 
  of 
  the 
  formation, 
  from 
  

   which 
  observations 
  they 
  were 
  able 
  to 
  indicate 
  that 
  the 
  beds 
  were 
  

   divisible 
  into 
  three 
  series 
  or 
  horizons. 
  

  

  